This invention relates to a belt retractor for a vehicle safety belt.
The energy-absorbing elements in a belt retractor act as force limiters which ensure that a controlled reverse rotation of the belt reel is effected in the direction of belt unwinding when excessively high forces act in the safety belt provided by the belt retractor. The level of force limitation is determined by the torsional resistance provided by the energy-absorbing elements and is changed in dependence on various influencing factors such as in particular the weight of the vehicle occupant to be restrained or the severity of the accident. In belt retractors known from the prior art, this is achieved by the selective coupling and uncoupling of individual energy-absorbing elements. From DE 200 04 674 U1, for instance, there is known a belt retractor comprising two energy-absorbing elements, each of which has a locking end with locking pawl. The two locking pawls are connected with each other by a connecting element, so that the engagement action of one locking pawl at the same time effects the engagement action of the other locking pawl. When the locking pawls are engaged, one locking end is non-rotatably connected with the frame, and the other locking end is non-rotatably connected with a holding ring, which in turn can non-rotatably be connected with the frame via a latch. When this latch is released, so that the non-rotatable connection between the holding ring and the frame is eliminated, the two locking ends can rotate relative to each other. The connection of the two locking pawls can be separated at a predetermined breaking point of the connecting element, so that the force acting against a rotation of the belt reel in the direction of belt unwinding solely results from the torsional resistance moment of an energy-absorbing element.
The invention provides a belt retractor for a vehicle safety belt, in which the force limitation level can freely be adjusted by a selective deactivation of energy-absorbing elements.
This is achieved in a belt retractor for a vehicle safety belt which comprises a frame, a belt reel rotatably mounted in the frame, at least a first and a second energy-absorbing element, which each has a connecting end and a locking end, wherein the locking ends each are provided with a locking disc and adapted to be selectively connected with the frame. The belt retractor further comprises a first and a second locking pawl which by means of at least one actuating device can each selectively be brought into engagement in one of the locking discs, wherein at least one switching device is provided, which can selectively prevent the engagement action of at least one locking pawl. In dependence on various influencing factors such as the weight of the vehicle occupant and/or the severity of the accident, the switching device can prevent that one or more locking pawls are engaged in the associated locking teeth in the case of a vehicle impact.
Further features and advantageous aspects of the invention can be taken from the sub-claims.